When I get a new Mac, one of the first things I always do is turn on Finder's Path Bar and Status Bar. Those features give me critical information for troubleshooting and moving around the file system, and heck, they're just cool anyhow. To turn ’em on, go to Finder's View menu and select Show Path Bar and Show Status Bar.
(If those options are greyed out, make sure you've got a Finder window open.)
When they're enabled, both the Path Bar and the Status Bar will show up at the bottom of Finder windows.
The Status Bar is pretty straightforward—it gives you the number of items in your current folder, followed by the amount of space you've got remaining on your drive.
If you're browsing the contents of an external drive (even if it's a Time Capsule!), the Status Bar will show you how much room you've got there, too.
My Time Capsule apparently has a ton of space left. I'm a happy camper.
The Path Bar is even more useful, though. It displays the hierarchy of where you are in your file system.
It's not obvious, but you can use the icons within the Path Bar to move around on your Mac, too. Double-click any of them to jump to that location, or Command–double-click one to open it in a new window. You can Control-click any of those icons to bring up a handy contextual menu, as well.
Really, I've gotten so accustomed to using the Path and Status Bars that I feel kind of lost without them. I'm a total Finder nerd! Yes, that IS an actual thing that I did not make up.